A wide variety of particulate-type food materials are available for purchase in commercial outlets. These foods include meals, powders, and granulated products that may be mixed with a liquid to produce common food substances. Detecting and preventing contamination of these substances is an important challenge facing the food industry.
For example, melamine, a common industrial chemical, has been intentionally mixed with food substances as a way to boost products' apparent protein content. Significantly, melamine has been found in powdered milk and milk substitutes intended for infant consumption. Melamine was also used as a binder when making pellet feed for animals. Consequently melamine-contaminated food is a major safety concern.
In addition to melamine, small amounts of cyanuric acid, ammeline, and ammelide were also detected in pet feed and in the tissue and urine of dead pets that consumed the contaminated food. Although it may be possible that cyanuric acid, ammeline, and ammelide were added as contaminants, it is more likely that their presence in pet food resulted from the degraded derivatives of melamine.
Prior art methods of detecting contamination in particulate food substances are effective, but may be relatively slow, and the tested food samples are relatively small in comparison to the speed and the size of samples that can be tested using the method and apparatus described herein. U.S. Pat. No. 8,467,052 to Chao uses a point-source laser to test particulate materials for contaminates. Although the Chao method is effective, it is not nearly as fast as the method described herein.
The need exists for a method and apparatus to more quickly test larger sample volumes of particulate-based materials. The current invention describes a method that reduces test times from hours to minutes, and significantly increases the size of samples to be tested. The current method and apparatus achieves these improvements while meeting or exceeding the accuracy and consistency of the prior art processes.